The invention concerns a device for covering transported printed sheets with powder having a reservoir for powder, an inlet feeding into the reservoir for a carrier air stream, an outlet feeding out of the reservoir for the carrier air stream containing powder and with a heating cartridge disposed in the reservoir.
Known in the art from DE-AS 1 252 703 and DE-PS 966 443 is e.g. a device for covering printed sheets with powder with which a carrier air stream is blown into a reservoir filled with powder so that this carrier air stream whirls up the powder contained therein. The air stream containing powder is guided from an outlet to the printed sheet which is to be covered with powder, via appropriate conduits. It has turned out that, although printed sheets can be covered with powder using a device of this kind, the quality of the covering depends strongly on the state of the powder in the powder reservoir. In the event of relatively high air moisture, there is the danger that the powder forms clumps in the powder reservoir and cannot properly be whirled-up. A reduced amount of powder is thereby carried out along with the carrier air stream so that the covering is insufficient. Although powder reservoirs of this type are equipped with a heating cartridge for introducing heat into the powder, this heat introduction is locally limited. Clumping of the powder cannot thereby be avoided.
It is therefore the underlying purpose of the invention to further improve a device of the above mentioned kind to prevent clumping to the greatest extent possible.